This invention relates to the processing of image information. In particular it provides a method and apparatus whereby a computer with limited capacity can nevertheless process a relatively large field of image information.
The invention can be used for processing image information of essentially any nature. In a typical instance the information represents a two dimensional array or field of values. Image processing within the scope of the invention includes, without limitation, such diverse practices as photography, television, printing and the graphic arts, and laser scanning. It further includes instances where there is no original scene, as encountered with images created with sonar techniques, with infrared techniques, with radar, with ultrasound and with computerized axial tomography (CAT) scanners as well as with other medical imaging instruments.
Image processing with a field of such information typically involves a vast number of concurrent operations, in order to process the information for all picture elements, i. e. pixels, of the field. The field-by-field processing of this information on a computer requires large and correspondently costly memory capacity to store the image information for all the pixels. For example, the computer storage of a square field having 512 pixels on a side, and in which one byte defines the field value for one pixel, requires a memory with a capacity of 262,144 bytes. The computer memory further must have at least twice this capacity to store such a field of input values and to store a like field of resultant values. More commonly, the memory requires three times this capacity, or over three-quarters of a million bytes, to store the pixel information for two input fields and for the resultant computed field.
It accordingly is an object of this invention is to provide a method and apparatus for processing image information with a computer having limited memory capacity relative to the size of the image field being processed.
Another object of the invention is to provide a method and apparatus which combines the aforesaid compact memory requirement with relatively high speed operation. The conventional full-reduction serial processing of a field of image information requires, as an elementary example, such undue time as to be essentially impractical.
A further object of the invention is to provide an image processing system in which one storage element is a photographic recording. A more particular object is that the system operate with plural references to the photographic, i.e. radiation-responsive, recording for input information. The term "photographic recording" (or record) is used herein in a broad sense to include a radiation-responsive record on a photochemical emulsion medium as well as on an electrostatic medium.
It is also an object of the invention to provide a method and apparatus of the above character suited for commercial application.
Other objects of the invention will in part be obvious and will in part appear hereinafter.